docs: def start_task(self, name, size):
          '''
          Add a task to the stack. If, for example, `name` is `'Iteration'` and
          `size` is 10, progress on that task will be shown as
  
              ..., Iteration <p> of 10, ...
  
          :param str name: A descriptive name for the type of subtask that is
              being completed.
          :param int size: The total number of subtasks to complete.
          '''
          if len(self.task_stack) == 0:
              self.start_time = datetime.datetime.now()
          self.task_stack.append(Task(name, size, 0))